A separation mechanism for separating a first object and a second object that are in a fixed positional relationship has conventionally been known. There is provided an OBS (Ocean Bottom Seismograph), for example, configured to be installed on a sea floor or at the bottom of the ocean to carry out measurement in order to conduct a seismic survey by sinking the OBS to the bottom of the ocean. In a seismic refraction survey to be conducted to study a mechanism of occurrence of an earthquake at the bottom of the ocean or the like, an artificial seismic wave is generated, and the sound wave refracted at a boundary surface between respective strata under the ocean bottom is received by a large number of ocean bottom seismographs installed at the bottom of the ocean at predetermined distances. Measurement is thereby carried out. The ocean seismograph thus used is formed by a combination of an ocean bottom seismograph body and an anchor (weight), and is sunk at the bottom of the ocean. The ocean seismograph body is the first object including therein a sensor and other parts and has buoyancy. The anchor (weight) is the second object for mooring the ocean seismograph body at the bottom of the ocean. After the measurement, a recovery operation of a body portion of the ocean seismograph is performed for data collection, device maintenance, or other purposes. The recovery operation is performed by operating the separation mechanism provided to separate the first object and the second object.
As the separation mechanism, there is a gunpowder method (disclosed in JP08-271291A (Patent Document 1)), an electric corrosion method (disclosed in JP2006-30124A (Patent Document 2)), etc. In the gunpowder method, an action of cutting a cable configured to connect the first object body and the second object is triggered by explosion of gunpowder. In the electric corrosion method, a metal plate (such as a stainless plate) or a metal wire, configured to connect the first object and the second object is electrically corroded forcibly to be cut. The first object and the second object are thereby separated.